Synergy of hydrophilic nanoparticle and nonionic surfactant on stabilization of carbon dioxide-in-brine foams at elevated temperatures and extreme salinities

Abstract

Stability of carbon dioxide foam attracts huge attentions while being of great challenge to many industrial practices. In this paper, aqueous CO2 foam stabilized with synergy of hydrophilic nanoparticles and nonionic surfactants was experimentally investigated at elevated temperatures and extreme salinities. The foam formula consisting of 1.5 wt% T40 and 2.49 mM C12E23 was determined under elevated temperature and salinity conditions. At 80 °C, the foam volume of the C12E23/T40 foam is 225 mL, and the half-life is 32 min, which is 13.9 times that of the C12E23 foam. At a salinity of 17 × 104 mg/L, the foam volume is 185 mL, and the half-life is 71 min, which is 24.4 times that of the C12E23 foam. With increasing salinity and temperature, the interfacial tension rises, and the viscoelastic modulus gradually declines, resulting in a lower foam stability. However, the T40/C12E23 foam has a good temperature and salinity tolerance, which can be used under harsh reservoir conditions. In a heterogeneous microscopic visualization model, water channeling in high-permeability regions inhibits the further increase in oil recovery. Subsequent injection of the C12E23/T40 foam improves the oil recovery factor up to 86.2%. The C12E23/T40 foam enhances the oil recovery by increasing the sweep area and flooding efficiency. In a sandpack model, the plugging pressure gradient of the CO2 foam stabilized by 2.49 mM C12E23 and 1.5 wt% T40 reaches 25.3 MPa/m, which is 12.65 times higher than that of the C12E23 foam. The composite reinforced foam attains good water blocking and profile control effects, thereby increasing the oil recovery factor 20.1% after water flooding. This study of great importance to improve not only the oil recovery efficiency, also anywhere where CO2-in brine foam applicable.